module ActionDispatch class RemoteIp class IpSpoofAttackError < StandardError ; end # IP addresses that are "trusted proxies" that can be stripped from # the comma-delimited list in the X-Forwarded-For header. See also: # http://en.wikipedia.org/wiki/Private_network#Private_IPv4_address_spaces TRUSTED_PROXIES = %r{ ^127\.0\.0\.1$ | # localhost ^(10 | # private IP 10.x.x.x 172\.(1[6-9]|2[0-9]|3[0-1]) | # private IP in the range 172.16.0.0 .. 172.31.255.255 192\.168 # private IP 192.168.x.x )\. }x attr_reader :check_ip, :proxies def initialize(app, check_ip_spoofing = true, custom_proxies = nil) @app = app @check_ip = check_ip_spoofing if custom_proxies custom_regexp = Regexp.new(custom_proxies) @proxies = Regexp.union(TRUSTED_PROXIES, custom_regexp) else @proxies = TRUSTED_PROXIES end end def call(env) env["action_dispatch.remote_ip"] = GetIp.new(env, self) @app.call(env) end class GetIp def initialize(env, middleware) @env = env @middleware = middleware @calculated_ip = false end # Determines originating IP address. REMOTE_ADDR is the standard # but will be wrong if the user is behind a proxy. Proxies will set # HTTP_CLIENT_IP and/or HTTP_X_FORWARDED_FOR, so we prioritize those. # HTTP_X_FORWARDED_FOR may be a comma-delimited list in the case of # multiple chained proxies. The last address which is not a known proxy # will be the originating IP. def calculate_ip client_ip = @env['HTTP_CLIENT_IP'] forwarded_ips = ips_from('HTTP_X_FORWARDED_FOR') remote_addrs = ips_from('REMOTE_ADDR') check_ip = client_ip && @middleware.check_ip if check_ip && !forwarded_ips.include?(client_ip) # We don't know which came from the proxy, and which from the user raise IpSpoofAttackError, "IP spoofing attack?!" \ "HTTP_CLIENT_IP=#{@env['HTTP_CLIENT_IP'].inspect}" \ "HTTP_X_FORWARDED_FOR=#{@env['HTTP_X_FORWARDED_FOR'].inspect}" end not_proxy = client_ip || forwarded_ips.last || remote_addrs.first # Return first REMOTE_ADDR if there are no other options not_proxy || ips_from('REMOTE_ADDR', :allow_proxies).first end def to_s return @ip if @calculated_ip @calculated_ip = true @ip = calculate_ip end protected def ips_from(header, allow_proxies = false) ips = @env[header] ? @env[header].strip.split(/[,\s]+/) : [] allow_proxies ? ips : ips.reject{|ip| ip =~ @middleware.proxies } end end end end